Dogsitting and diapers on dogs

I am a regular dogsitter and am pretty savvy with dogs, but the one I have got right now is giving me a challenge.

She is a 14 year old dog who is pretty spry and with it. She has separation anxiety that is destructive when left alone, so her owner crates her when she is left alone and gives her medication to help calm her (100mg trazodone and 100mg gabapentin). She sometimes has anxious incontinence, so the owner puts a diaper on her when she is crated, and provided me with two reusable diapers and I am going to supplement with disposables because I have to handwash the reusables.

Owner described her break schedule as every 5-6 hours and that she sleeps through the night and goes 'whenever' in the morning, no strict time.

This is not playing out well with me, maybe because anxiety, maybe new place/person, maybe because she's old, maybe all of that. She has steadily been asking to go out every four hours, and wakes me up to do so all night. During the daytime, not such a big deal but I need to sleep and I am not sure of the best options.

She does use the diapers in the crate and they are fancy high absorbent ones, so I could put one on her at night but I am concerned about potentially being in a wet one for awhile; I took her out at 12am last night, and she woke me at 4:10am and again at 8:30ish so if I put one on her at 12am she could potentially be wet for 4ish hours. I could give her a bird bath when i get up to make sure she's clean, but not.sure if 4 hours is too long. I could crate her without a diaper but then she's potentially laying in urine and will need a bath.

Owner is surprised with these issues, he does not have her waking in the night to pee. She has had one accident in the house which also does not happen for him. She has free access to water with him, because of the accident and frequency of need, I am providing ample water at meals and then taking it away. Doing that last night did not stop the middle of the night wakeup.

Looking for thoughts on the use of diapers overnight or honestly any other solutions folks might have. I am exhausted.